To speak of this subject you must... explain the nature of the resistance of the air, in the second the anatomy of the bird and its wings, in the third the method of working the wings in their various movements, in the fourth the power of the wings and the tail when the wings are not being moved and when the wind is favourable to serve as guide in various movements.

He who has access to the fountain does not go to the water-pot.

Truth is so excellent, that if it praises but small things they become noble.

The color of the object illuminated partakes of the color of that which illuminates it.

Lying on a feather mattress or quilt will not bring you renown.

The memory of benefits is a frail defence against ingratitude.

It is useful to constantly observe, note, and consider.